Electromagnetic detector responsive to a modification of a magnetic field

摘要

An electromagnetic detector designed to monitor road traffic, responsive to a modification of an electromagnetic field produced by the presence of a metallic mass in the vicinity thereof, comprises a metal base on which are disposed a transmitting coil creating a field and a receiving coil whose axis deviates from the perpendicular to the base. The receiving coil detects a measuring field created by the currents induced in the base by the transmitted field. The processed signal is the resultant of the signal produced by the presence of a metallic mass in the transmitted field and by the signal due to the measuring field.